Apparatus for the fluid treatment of textiles using molten metal



N v- 1954 R. s. E. HANNAY E L APPARATUS FOR THE FLUID TREATMENT OF TEXTILES USING MOLTEN METAL 2 Sheets-Sheet 1 Filed May 2, 1949 Q mm wmmm mm w mm mi 1 n ven tor-1 fie? iff/MW/Mzwney torneys Nov. 9, 1954 5 HANNAY ET AL 2,693,689

APPARATUS FOR THE FLUID TREATMENT 0F TEXTILES USING MOLTEN METAL 2 Sheets-Sheet 2 Filed May 2 1949 treating liquor with application of heat.

Unite States Patent APPARATUS FOR THE FLUID TREATMENT OF TEXTILES USING MOLTEN METAL Robert S. E. Hannay, Carlisle, and William Kilby, Camforth, England, assignors to Standfast Dyers & Printers Limited, Lancaster, England, a British company Application May 2, 1949, Serial No. 90,998

Claims priority, application Great Britain May 4, 1948 7 Claims. (Cl. 68-9) This invention relates to treatment of textile and like materials in which the material is impregnated with a Examples of such treatments are dyeing, developing, bleaching and scouring, and the present invention is applicable, more especially, but not exclusively, to dyeing. The term textile materials is intended to embrace various materials as used in the textile industry, for example, cotton, wool, rayon, nylon, and other natural or artificial materials, and fabric, felt, sheets, webs or yarns made from glass or synthetic plastic materials. The term textile is not intended to restrict the scope of the invention to woven material. (Such materials are hereinafter embraced within the term materials.

The present invention refers more specially to a method of continuous treatment as described in our copending United States Application Serial No. 722,042, filed January 14, 1947, in which the material is passed through a bath of molten metal which may have a melting point below about 100 C. and preferably below about 80 C., the material prior to entry to the bath being continuously impregnated with a treating liquor which is fed to the material in uniform strength and quantity throughout its length. The feeding of the liquor to the material may advantageously be effected by floating the treating liquor as a layer on the top of the metal bath where the material enters the same.

The invention is, however, applicable to any treatment of the kind in which the material is passed through a molten metal bath.

The treatment in the molten metal bath comprises application of both heat and pressure, and provision must be made to supply the heat in such a manner that the temperature is as uniform as possible. We have made experiments to ascertain the most advantageous form of the molten metal bath, and have discovered that the passage of the material through the metal sets up eddy currents in the molten metal. By placing the heating elements, for example steam pipes, adjacent to, but not contacting with, the moving material, a satisfactory arrangement is arrived at. If the heating elements are remote from the material and the metal bath is consequently large in volume, convection currents are set up resulting in uneven patches of temperature. Further, any heat abstracted from the metal by the material remote from any heating element is liable to cause local cooling. It will be obvious that the width of the metal bath must be suflicient to allow for the thickness of the material being processed.

We have also discovered that contact by the material with a heating element is injurious to the result.

Thus in accordance with the present invention we provide apparatus for continuously treating material in continuous length, comprising a treating vessel formed with a narrow elongated passage therethrough for passage of the material, the walls of said passage having inset or incorporated therein the main heating elements and said walls being spaced so that the distance from the material to the surface of any main heating element is not less than one eighth of an inch and not more than one inch. The walls may be jacketed and themselves form the main heating elements.

In further accordance with the present invention the apparatus comprises a treating vessel formed with a narrow elongated passage therethrough for passage of the material, and steam pipes, flue pipes or tube-like electrical heating elements arranged parallel to the plane of ice adapted to support the heating elements or may form,

one part of a steam or liquid chamber and thereby themselves comprise the heating elements.

Contact by the material with the stationary wall of the passage is, as aforesaid, injurious to the result, and the shape of the wall may be a compromise between this and the desirability of economising as far as possible in the volume of metal needed to fill the bath. Where the sides of the wall are formed with recesses to receive the heating elements the recess is formed so as to facilitate the entry of the eddy currents to the heating elements. It is clear that the walls of the passage may be as far apart as desired, but such parts of the wall that provide heat for the treatment must conform to the limitations mentioned above.

Auxiliary heating elements may be fitted at a greater distance from said passage for the purpose of unfreezing the metal of the bath as a whole.

Embodiments of the invention will now be described, but simply by way of example, with reference to the accompanying diagrammatic drawing in which:

Fig. 1 is a sectional view showing the continuous treatment of a length of cloth and one form of cloth heater.

Fig. 2 is a sectional detail view showing the cloth passing through another form of cloth heater, and

Fig. 3 is a sectional detail view showing the cloth passing through yet another form of cloth heater.

Fig. 4 is a sectional plan view of the line 44 of Fig. 1.

Fig. 5 is a fragmentary view in the direction of arrow 5 (Fig. 1).

Fig. 6 is an alternative form of metal bath.

Fig. 7 is yet another form of metal bath.

Fig. 8 is an enlarged view of the adjustable metal rod 20 and its housing.

Referring to Fig. 1, cloth 1 in continuous length as shown in chain-dotted lines passes in the direction of thearrows over steam cylinders 2 adapted to heat the heaviest cloth travelling at the highest speed, to a temperature somewhat above 70 C. The apparatus may also be used for lighter cloths at lower speeds, overheating of the cloth not being serious, as the steam temperature is not high (15 pounds pressure).

In Fig. 2 an alternative arrangement for cloth heating consists of a casing 3 through which the cloth 1 passes and through which hot air is forced by a fan 4, the air temperature being such that the arrangement may be used for lighter cloths at lower speeds without risk of serious overheating.

In Fig. 3 a further alternative arrangement for cloth heating consists of pairs of opposed electrical radiant heating units 5 spaced along the cloth length, the cloth passing between the units of each pair. Control of cloth temperature is obtained by switching units on or off selectively. The heated cloth 1 for the purposes of dyeing passes over rolls 6 and directly down into the molten metal bath vessel 7 having a single entry pass at 7A and a single exit pass at 78, around a bottom roll 8. The dyed cloth then passes away to roll 9.

The top of the bath vessel 7 is of enlarged width as shown and the surface of the molten metal is indicated at 10. The dye liquor is contained in an open-bottomed metal dye box 11A extending into the metal bath and floats as a layer 11 on the surface of the molten metal.

The layer of liquor 11 on top of the metal bath 7 is maintained at a comparatively small volume, and as it is absorbed by the material, it is substantially continuously replenished with fresh liquor in order to maintain the condition of the liquor in said layer such that variations in temperature, volume and strength of a magnitude likely adversely to affect the treatment are avoided, and the replenishing liquor is heated as it is supplied to said layer. Preferably the volume and strength of the liquor in said layer are maintained substantially constant.

In this way the liquor is heated and is very quickly thereafter absorbed by the.

material. Thus prolonged heating, and therefore formation of sludge as hereinafter explained, is avoided. Moreover, the temperature of the liquor ismaintained. substantially constant. andis prevented firom. falling undesirably'lbw- 'Intheexample, the. dye liquor is fed by apump 12 from a sup ply tank 13 through. a conduit 14 to a. smallcapacity heating-tank 15 A .feedvalve 116 in the conduit 14 is electrically controlled'( as hereinafter described) by the level of the liquor' in the layer 11 on the surface 'of-themetalbath 7. As the level of the said layer 11 dropsthe feed valyezl6i is opened. inorder to allow entry of more liquor to the heating'tankv 1 5,. and this causes the: already heatedliquor thereinjto overflow therefrom through-a conduitlAA. to the. box. 11A, thereby raising theflevelof said layer Hi again.

The liquor {in the :heating. tank 15- is-heated by a coil oftubing 17 supplied .with steam from. a thermostatically controlled steamvalve 18, thethermostat having contacts 1 9 in the said heatingtank 15.

The liquor innthe supply tank 13 is maintained at a relatively low temperature of about C. to 301 C. and is heated during its passage through theheating tank 1-5 up to about 80 C. Thusit is at. this relatively high temperature for only a short period before it is absorbed by the cloth 1 passing through the metal. bath 7.

The feed. valve 16? is controlled by the level of the liquor layer 11 by the following; arrangement:

A vertical tube is inserted in the open-bottom box 11A which houses the layer of dye on the metal surface 10. The liquor boxes 11 may be maintained at an average depth, of; for example, 12 inches. With a cloth width of say 50 inches, the relatively small quantity. of one-half to-one gallon of dye liquor is 111 use as compared with the 30- to gallons normally used, for instance in. a dye jig.

Said tube is provided at its upper end with. an insulating stopper 51 an adjustable metal rod 20 connected through a relay 21 to an electric battery 22 which is connected to the box 11A. The tripping, ofthe relay 21 actuates the said liquor feed; valve 16 which is. connected to the relay by leads 23.

When the liquor layer 11 rises andcontacts themetal rod: ZQ thecircuib operates to close thefeed'valve 16, and: when the-liquor drops down below the metal rod 20 the'feedvalve 16.. is opened.

It isfound: that the caustic solution of a. dye liquor 11- isliable' to form froth. on, the surface,- and as froth bubbles. act. as conductors in the same manner as the liquid,.,and; would thus give a false indication, a-small quantity of turpentine. or other suitable lliquid-v may be floated on the surface; of'thetliquor layer 11- and this malkezsflor 'break-scontact with the-lower end of; the metal r0 Inanother example the liquor is fedtby gravity through a feed valve controlled by thealevel. of the. liquor layer 11. It then passes through a heaterv of any convenient type and so intothe, liquor layer 11.

As the effectiveness of the heater and the. avoidance of any localized: overheatingv of the. liquor depends on the. rate. of the liquor flow,.a.nd the. liquor flow may be required to cease. temporarily, aconduit-24. is provided which connects the box: with the conduit;14- so that. the pump 12' may withdraw-liquor from. the liquor layer 11 and discharge said liquor into the conduit 14 connecting the feed valve- 16 to thez-heater 15'. A circulation valve 25in the conduit 24 is electrically controlled by the. relay 2L which operates. toopen. the. valve 25 when the valve 16 is closed, and vice versa. In this manner the liquor flow. throughthe heater 15-is constantly maintained. The. supply of 'steamto, the heater 15 is conthrough which downwardly projects trolled by the thermostat 19 situated on the discharge side of the heater.

In. certain cases it may bedesirable tofit a valve 18 controlling the supply of the steam, which valve is operated simultaneously with and inrelation to, the feed valve 16. In this case thev thermostat 19 will-joperate a valve or resistance adjusting the amount. of steamavailable when the control valve- 18.is opened.

As shown in Figures 1, 4- and 5, the-bath vessel 7 comprisesside plates 26, 27 arranged closely together opposite each other. A central'partition 28 is also provided, and between the parts 26, 27 and 28 the bath proper is provided, and it will be evident that the bath proper thus around the roller s at the bottom, then return pass prior'to leaving the metal;

close together,

' theopposite. direction.

performed has a minimum of volume thereby requiring a minimum amount of the relatively expensive bath metal, and requiring a minimum of heating;

The path of the cloth through the bath is indicated at 7A and 7B in chain-dotted lines; and the heat is communicated to the metal at intervals throughout the whole of said bathby a series of steam pipes as indicated at 29 on each side of the cloth 1. during its single entry pass 7A and its. single exit pass 7B. Steam for the pipes 29 issupplied through a valve 30 controlled by a thermostat having its terminals 31 in the molten metal of the bath 7. The metal intimately communicates the heat to the cloth 1 without chemically co-acting with the material or the dye liquor and it does not'absorb the dye liquor; while the metal is not absorbed by the cloth 1. It will also be evident that in this way not only may the temperature of the process be easily controlled, but depending upon the depth and specific gravity of the metal bath, thepressure applied to the cloth may be "controlled.

In this example, the width A of the passage is about /2 inch, and this enables effective operationwhile'requiring a comparatively small volume of metals The passage is of general U-shape with a verticaL downwardlp'as's' then up in-ta vertical By keeping: the passes substantially upright, tendency for the material to float transversely of its length-, where it might stick or scrape on the passage walls, is-avoided, the-flotation tendency being in the-vertical direction and'longitudinally of thematerial. The materiallrnay be centered in the passage by external guide rollers.

The pipes 29 extend transversely along thewal'l surfaces, being insetflush therein atsp aced interval's and on opposite" sides of the passage. The distances-B and C between the material 7B a-ncl the surfaces orthe pipes29 are-each approximately one quarter of an inch.

in a further-- modification the centeringof the r'nater-ial at entryt'o and exit fromthe-bath may be doneby passing the material; between two-vertically spaced guides (as shown which overlap-in the vertical direction, the 'mate- 1 rial-'thus-being-held against the lower guide-by: theiupper, I and thereby being automatically positioned.

In the example: shown in Figs-6, a-'Ufi-shaped: passage is provided by locating 'a series of superimposed h'orizontal rollers 40 between opposite walls-ofa- 'somewhat-wider vertical trough 41 the rollers 41% being comparatively but:'the re-entrant spacebetween eachzr oller and the next adjacent roller being filled in=-by a.- box'. 42 in which heatingmeans 43-are provided, whereby an elongated-passage of U sha-pe is: provided.

' In this'example, the lowermost-roller 40 is of less diameter than: an uppermost roller 40; whereby the material is constrained during the entry pass 7A- to a slight-angle out from. the-vertical; and duringthe exit: pass 71B, at..a slight angle out from the. vertical at the opposite; side in Inthisway'there is aslightcomponent of flotation-upthrust causingL thematerialt'oikeep in contact-with therollers 40. The'rollers' may. be idling or theymaybepositively. driven, and exter-nal guideirollers may beadded ifcontinuous and substantial contact: with the rollersisdesired.

In the example shown in; Fig. 7,. the treating'vessel includes: a relatively largediameter when 441 surrounded by a box. or vessel 45' whose inner walls 45A are: close to the roller- 44,;thereby leaving a spacexDL-ofi about /a inch for'the molten metal and' defining a.-passage; for .the material. Thus the material enters andileavesnear the top. oh the roller- 44-.. Ithas-been discovered that the temperature of) roller 44@ mustnbervery' approx-imatelythe samer'as. the temperature of the molten: metal: if-"even results-are tobe'obtained; 'Consequently ,,the. roller; may be heated; either; by allowing-.a-part of. its surface (-as shown) to'contact the-molten metalor by-meansof circulating moltenametalthrough -an annular space 44. inthe rol1er-as indicated in-phantom lines. Theheating of jthe molten metal is most satisfactorily performedg-as previously 'describedusing pipes 29-insetz intothe. wallsof the vessel 45. Treating liquors may fioat-on-the. metal surface, at entry and. for exit.

Two or more webs or equivalent formations. of materialmay be passed through. the." metal bath ,in parallel formation. Wherethereisa. dye bath. at. entry this .Imay be common to the websorthe. like, but where it. is desired. to. preheat the. Webs or the. like, this preheating; is on each-web-individually. -A.common. exit bath may also be provided. Apart from this, however,

it is desirable that each web or the like should be treated individually.

It will be noted that the box 11A at its lower part where it enters the metal, is of a width of the order of the width A of the molten metal passage through the bath, i. e. /2 inch.

As indicated in dotted lines at 32 the cloth 1 may in addition to or alternatively to passing through the layer 11, pass through a trough 33 in order to take up treating liquor. In this case, the level of the liquor in the trough 33 is maintained constant and is supplied from a main supply tank (not shown). The trough 33 may be located to receive the cloth prior to heating of the cloth by the cylinders 2.

In the example, with bath metal at 90 C. to 95 C. having a melting point of about 70 C. and with a treating liquor 11 floating thereon at about 80 C. to 85 C., the cloth 1 should be preheated so that at entry to the treating liquor 11 its temperature is such that having regard to the specific heats of the cloth 1 and of the treating liquor 11 and any thermal effect arising from their mixing, the temperature of the combined cloth 1 and treating liquid 11 is not lessthan 75 C.

For example, a textile material 1 having a specific heat of 0.3 absorbs 130% by weight of treating liquor 11 of specific heat 1.0 at 80 C. and should enter the treating liquid at 72 C. if the combined temperature is to be 785 C.

It is desirable to maintain the temperature of the bath metal not greater than about 90 C. to 100 C., as at higher temperatures, with an aqueous impregnation, steam may be generated below the surface of the metal and pass up through the metal bath and interfere with the even application of the dyeing liquor, and causing streaky dyeing.

The temperature to which the cloth 1 may be heated with safety will depend on circumstances, and in the case of materials previously impregnated with aqueous liquors the limit will be about 100 C., but in the case of dry cloths, for example, the limit will be that dictated by the fibres resistance to deterioration. For ordinary purposes 120 C. might be regarded as an upper limit.

The cloth on leaving the bath 7 passes through a box 34 projecting into the metal bath and containing salt solution 35 which floats on the surface of the molten metal. Salt solution is supplied to the box 34 by gravity from a tank 36 heated by steam pipes 37. Steam to the pipes 37 flows through a valve 38 which is controlled by a thermostat having its terminals 39 projecting into the tank 36. The salt solution in the box 34 is maintained at constant level by overflowing on to the surface 10 of the molten metal.

In a method of dyeing of the kind aforesaid with vat or sulphur dye liquors, where hydrosulphite is utilized, there may be a tendency for the hydrosulphite decomposition products to attack the molten metal of the bath 7 and to form a sludge on the surface 10 of the metal bath, and this sludge and some of the metal may adhere to the cloth and will adversely afiect the dyeing operation.

In further accordance with the present invention, we provide a method of dyeing of the kind aforesaid in which the vat or sulphur dye liquor has added thereto an antioxidant such, for example, as a reducing sugar, especially glucose, or a higher organic aldehyde, for example benzaldehyde, or tannic acid. The addition of such substances has been found to inhibit the formation of said sludge.

Any material passed through a metal bath will tend to be coated with metal unless the material contains sufiicient moisture. In cases were the metal temperature is 100 C., or below, at least about 80% by weight of moisture is necessary on the material to prevent metal adhesion. This percentage will, however, vary from material to material. In cases Where the metal temperature is over 100 C., say 120 C., less moisture is necessary as a minimum to prevent metal adhesion owing to the ebullition that takes place and the consequent resistance to metal absorption. Satisfactory results have been obtained with 60% of moisture by weight under these conditions.

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:

1. Apparatus for the continuous treatment of textile material in continuous length comprising a vessel, means in said vessel to force a treating liquid into said textile material, said means comprising a bath of molten metal, said molten metal having a melting point not more than about C., heating means to maintain the metal of the bath in molten condition at elevated temperature, two horizontally spaced open-bottomed troughs positioned within said vessel at the upper region thereof with the open bottoms of the trough extending downwardly beneath the surface of the molten metal bath, means to guide said textile material downwardly through one of said troughs into the bath of molten metal, through said bath, and out of said bath into the other trough and out of said other trough, means to supply liquid to each of said troughs, means to heat the liquid supplied to said first trough so that the liquid delivered to said first trough is delivered at an elevated temperature, means to maintain the liquid in said second trough at an elevated temperature and means to preheat said textile material so that the textile material enters said first trough at elevated temperature.

2. Apparatus for the continuous treatment of textile material in continuous length comprising a vessel, means in said vessel to force a treating liquid into said textile material, said means comprising abath of molten metal, said molten metal having a melting point not more than about 100 C., heating means to maintain the metal of the bath in molten condition at elevated temperature, two horizontally spaced open-bottomed troughs positioned within said vessel at the upper region thereof with the open bottoms of the troughs extending downwardly beneath the surface of the molten metal bath, means to guide said textile material downwardly through one of said troughs into the bath of molten metal, through said bath, and out of said bath into the other trough and out of said other trough, means to supply liquid to each of said troughs, means to heat the liquid supplied to said first trough so that the liquid delivered to said first trough is delivered at an elevated temperature and means to maintain the liquid in said second trough at an elevated temperature.

3. Apparatus for the continuous treatment of textile material in continuous length comprising a vessel, means in said vessel to force a treating liquid into said textile material, said means comprising a bath of molten metal, said molten metal having a melting point not more than about 100 C., heating means to maintain the metal of the bath in molten condition at elevated temperature, an open-bottomed trough positioned within said vessel at the upper region thereof with the open bottom of the trough extending downwardly beneath the surface of the molten metal bath, means to guide said textile material downwardly into said bath of molten metal, through said bath, and out of said bath through said trough, means to impregnate said textile material with a liquid before said textile material enters the molten metal bath, means to supply liquid to said trough at an elevated temperature and means to preheat the textile so that the textile material enters the molten metal bath at elevated temperature.

4. Apparatus for the continuous treatment of textile material in continuous length comprising a vessel, means in said vessel to force a treating liquid into said textile material, said means comprising a bath of molten metal, said molten metal having a melting point not more than about 100 C., heating means to maintain the metal of the bath in molten condition at elevated temperature, an open-bottomed trough positioned within said vessel at the upper region thereof with the open bottom of the trough extending downwardly beneath the surface of the molten metal bath, means to guide said textile material downwardly into said bath of molten metal, through said bath and out of said bath through said trough, means to supply liquid to said trough and maintain the liquid in the trough at elevated temperature, and means to impregnate said textile material with a liquid before said textile material enters the molten metal bath.

5. Apparatus for the continuous treatment of textile material in continuous length comprising a vessel adapted to contain a bath of molten metal, partitioning means within the vessel, the partitioning means and the inner faces of said vessel together defining a passage of U shape, means in said passage to force a treating liquid into said textile material, said means comprising a bath of molten metal, said molten metal having a melting point not more than about 100 C., heating means to maintain the metal in molten condition, means to guide said textile material 7 into, through and out of said passage, means to impregnate the textile material with a liquid before the said textile material enters the molten metal bath and means to preheat the textile material so that the textile material enters the bath of molten metal at elevated temperature.

6. Apparatus as recited in claim 5 in which means are provided to heat the textile material as it emerges from said bath of molten metal.

7. Apparatus for the continuous treatment of textile material in continuous length comprising a vessel, means in said vessel to force a treating liquid into said textile material, said means comprising a bath of molten metal, said molten metal having a melting point not more than about 100 C., heating means to maintain the metal of the bath in molten condition at elevated temperature, partitioning means within said vessel, the partitioning means and the inner faces of said vessel together defining a passage of U-shape, an open-bottomed trough positioned within said passage at the upper region thereof with the open bottom of the trough extending downwardly beneath the surface of: the molten metal bath, means to guide said textile material downwardly through said trough into the bath of molten metal, through said bath, and out of said bath, means to supply liquid to said trough, and means connected to said liquid supply means to heat said liquid supplied to said trough so that the liquid delivered to said trough is delivered at an elevated temperature.

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